I have read on a couple of websites that door rattles on early GTs are common but nowhere does it say the cause or a fix. Before I consider tearing the door apart does anyone have experience of this and can guide to the cause and a fix?

 

No help but my 2004 has doors that rattle!

 

Maybe take the inner door panel off, use a sheet of Dynamat on the metal door surface, then remount door panel yet USE NEW plastic push-on pieces.